EEG Training Research Articles

Bayesian classification of index finger movements by analysis of MEG and EEG data

Abstract A Bayesian classifier was developed for decoding finger movements by analysis of MEG data. Subjects were monitored by a 151-channel MEG system while making “flicking” motions (up, down, left, right) of the right-hand index finger. The SAM beamformer method was used to spatially localize the brain activity. A classifier was constructed based on signals from 30 to 200 discriminating locations selected from the 1-mm grid. When applied to the test data, 4-way classification rates in the range 50–70% were observed (chance = 25%), with information rates of 0.25–0.7 bits per classification. In several cases simultaneous EEG recordings were made. By calculating regression of SAM signals from discriminating locations on EEG training data, it was possible to accomplish the “informing” of the EEG by MEG. It was shown that even when classification using physical EEG channels failed, informed EEG yielded 40–45% classification rates.

Phase Sensitivity of Bipolar EEG Training Protocols

Introduction. When performing bipolar EEG training the reward waveform is dependent on the phase relationship between the two sites at the center frequency of the reward band. It is also driven by the instantaneous amplitude at the two sites. Effectively, the training rewards an increase in differential mode activity while discouraging common mode activity. This follows from the fact that the in-phase component of the signal is suppressed in the differential amplifier, and only the out-of-phase component of the waveforms is propagated and rewarded. These relationships can be represented visually with a vector calculation. Method. Two vectors representing the signals at the two sites at a given frequency were combined with varying phase angle and for several representative magnitudes to yield the net output amplitude. Surrogate data were used to obtain distributions illustrating the above functional relationships. Results. Varying phase angle between the two vectors has the greatest effect on the resultant magnitude when there is a high degree of amplitude parity. The influence of phase is more modest when comodulation is low. In cases of high amplitude disparity bipolar training reduces effectively to single-site or referential training. Discussion. The theoretical rationale behind bipolar training as a primary approach to self-regulation is modest at this time. The present modeling of signal interaction illustrates that phase relationships play a governing role in bipolar training in the general case. That dependence is modulated by the degree of comodulation between the sites. Hence, bipolar training may activate different mechanisms of control depending upon the degree of amplitude parity between the two sites. The incorporation of such thinking will likely lead to a further refinement of treatment protocols.

Clinical Neurophysiology: EEG–Video Monitoring

Clinical Neurophysiology: EEG–Video Monitoring

Kathleen Mears Memorial Lecture: ASET and OSET, Patterns and Parallels

ABSTRACT.OSET is the international Organisation of Societies for Electrophysiological Technology, a federation of professional societies from around the world. Just as ASET grew out of the national physicians' society, OSET grew out of an international physicians' consortium. Both ASET and OSET are independent groups that address the many issues specific to technologists, from entry-level education to standards of practice and legal conditions of practice. The present “members” of OSET are the technologist societies of Australia, Canada, Denmark, Finland, France, Germany, Italy, Netherlands, Norway, Sweden, Switzerland, the UK, and the US; the individual members of those societies are members of OSET by extension. OSET holds a week-long Congress every four years, hosted by one of the member societies. Technologists from all over the world gather to share information via platform papers and posters. Just as ASET meetings provide an opportunity for technologists to learn from each other, formally and informally, so the OSET Congresses extend that sharing beyond national borders. Between Congresses, OSET work is done by committees. Some of the published results of this committee work are statements of minimal and optimal standards of training in EEG and evoked potentials, guidelines for digital EEG, guidelines for infection control, and guidelines for intraoperative monitoring. The last two Congresses have had sessions on education in the OSET countries; present committee work is continuing to study this issue to develop a truly international statement of competencies, i.e., what technologists must be able to do to perform electrophysiologic studies anywhere in the world.

TOVA Results Following Inter-Hemispheric Bipolar EEG Training

ABSTRACT Introduction. This study examines recovery of attentional measures among a heterogeneous group of clients in a pre-and post-comparison using inter-hemispheric EEG training at homologous sites. A continuous performance test was used as an outcome measure. The client population was divided into three categories: (a) primarily attentional deficits, (b) primarily psychological complaints, and (c) both. Method. Neurofeedback protocols included T3-T4, Fp1-Fp2, F3-F4, C3-C4 and P3-P4. A wide range of reward frequencies was used, and these were individually selected to optimize the subjective experience of the training. Participants were 44 males and females, 7 to 62 years old, who underwent treatment for a variety of clinical complaints. Dependent variables were derived from a continuous performance test, the Test of Variables of Attention (TOVA), which was administered prior to EEG training and 20 to 25 sessions thereafter. Results. After EEG training a clear trend towards improvement on the impulsivit...

A Neurologist's Advice for Mental Health Professionals on the Use of QEEG and Neurofeedback

I am a practicing neurologist. I graduated from medical school in 1960 and finished my residency in 1965. I had the usual electroencephalography (EEG) training during my residency which involved three months of reading EEGs side by side with an electroencephalographer (Ralph Druckman). I learned EEG by the apprentice method. At first, he would point out what was real and what was artifact. Then he began to point out various transients and to ask what they represented (artifact, normal physiology, or some type of pathology). At first, he would dictate the reports, always emphasizing the clinical relevance of the findings and suggesting possible treatment. Recognition of epileptiform activity was strongly emphasized, as well as recognition of focal or generalized slow wave activity. The importance of digital analyses and databases was not yet recognized (paper EEG only). When I finished my residency, I entered academic medicine and the EEGs were read by more thoroughly trained (board certified) electroenephalographers. Later I became associated with an epilepsy monitoring unit, took additional training in EEG, and became board certified in EEG. Then, I began to read EEGs on a daily basis, eventually interpreting several thousand. When the first QEEG machines came out, I got one and learned about the additional difficulties of using and interpreting QEEGs. The QEEG databases and discriminants developed by E. Roy John (John, Prichep, Fridman, & Easton, 1988) proved more helpful than raw EEG in differential diagnosis of nonepileptic problems (dementia versus depression, unipolar versus bipolar depression, multi-infarct dementia versus Alzheimer’s, performance anxiety versus ADD, etc.). Later work by Suffin and Emory (1995) showed that QEEG

The clinical relevance of EEG interpretation.

There is need nowadays to re-emphasize the capabilities of electroencephalography: a method representing the extremely important function/dysfunction-orientation in neurological thinking and practice. Valuable and relevant messages to the clinician naturally require solid EEG training and the resulting expertise. The idea that valuable EEG information is limited to the field of epileptology is erroneous. A plethora of clinically relevant messages can be derived from the EEG in nonepileptic conditions and, above all, in metabolic (and so called "mixed") encephalopathies where neuroimaging has almost nothing to offer. The discussion of EEG and epileptology only skirts pediatric conditions (and most of the epileptic syndromes). It is shown that EEG reading in epileptology is a lot more than simply "hunting spikes." A strong plea is being made against the presently fashionable overuse of the term "non-convulsive status epilepticus." Continuing neglect of functional/dysfunctional orientation can seriously endanger the entire field of Neurology.

Behaviorism and Neurofeedback: Still Married

ABSTRACT Many behavioral science practitioners do not appear to understand basic behavioral concepts and may easily misuse and misunderstand behavioral language. The notion that the non-linear nature of the neural system requires a perspective based on either general systems theory or chaos theory in order to describe EEG training, and that a behavioral conceptualization is inadequate, is unjustified. All aspects of effective EEG training programs can be described in behavioral terms. Behavioral language is particularly useful for identifying and describing important components of the training procedure.

EEG Biofeedback on a Female Stroke Patient with Depression: A Case Study

ABSTRACT Background. This single case concerns the treatment of a 71-year-old female stroke patient. The patient's MRI revealed that the location of the stroke was in the right side basal ganglia with damage extending into the anterior limb of the internal capsule. She presented with a virtual paralysis of the left side of her body (hemiplegia with immobilized left arm, contracted fist, minimal motor control over left leg, absence of muscle tonus in left side of face and slurred, monotonic speech). Method. The client was provided with EEG biofeedback training on a one to two half-hour sessions per week schedule. Bipolar montages were used along with single site protocols. This was based largely on the idea of reciprocal communication loops between widely separated cortical generators. It was thought that encouraging communication between cortical sites would have a beneficial impact on impairments related to both functional and structural damage. EEG training protocols included SMR (12-15 Hz) enhancement ...

Technical Issues Involving Bipolar EEG Training Protocols

Technical Issues Involving Bipolar EEG Training Protocols

Changes in Lateralized Memory Performance in Subjects with Epilepsy Following Neurofeedback Training

Both seizure reduction and neuropsychological improvements have been reported following neurofeedback training directed to normalization of the sensorimotor EEG. These findings could be interpreted as nonspecific effects rather than specific changes brought about by EEG training. The present study demonstrated neuropsychological changes of a selective nature that would be difficult to interpret as nonspecific. Epileptic subjects with unilateral temporal lobe lesions were administered memory tests prior to EEG training, after control training, and after sensorimotor EEG normalization training. Successfully trained subjects showed exclusive improvement on memory tasks specific to the hemisphere contralateral to their lesion, and no improvement on memory tasks specific to the hemisphere with the lesion. Such selective changes are difficult to interpret as nonspecific effects of participating in a study, and would seem to require genuine alteration of neural substrates as a result of EEG training.

Clinical neurophysiology training and certification in the United States: 2000

To the Editor: Burns et al. reviewed clinical neurophysiology (CNP) training in the United States.1 Since the approval of CNP as an added qualification examination and the establishment of CNP fellowships, EMG and EEG training have changed. We agree that there is limited exposure to CNP during residency and that additional training is often required. However, as currently structured, we believe CNP training has become too diluted, creating CNP generalists rather than focused experts, as was the case formerly. Burns et al. acknowledge that CNP training is not designed to make experts in each CNP area, but rather provides greater knowledge and skill than obtained during residency. One might ask where future EMG and EEG experts will come from, if not from CNP fellowships. The majority of residents pursuing fellowship training still do so in preparation for an academic career.2 It would appear unlikely that many candidates will opt for training beyond one additional fellowship year. We have had the opportunity to train fellows in 6-month, 12-month, and 2-year programs devoted solely to EMG/neuromuscular disorders. The largest growth in expertise occurs between 6 and 12 months, when fellows consolidate their knowledge, increase their confidence and procedural skills, and solve difficult problems independently. As currently structured, EMG training is particularly handicapped in CNP fellowships, because the equivalent of 12 months EMG training cannot …

Is there chaos in the brain?

AbstractFor some years there has been a controversy about whether brain state variables such as EEG or neuronal spike trains exhibit chaotic behaviour. Wright & Liley claim that the local dynamics measured by spike trains or local field potentials exhibit chaotic behaviour, but global measures like EEG should be governed by linear dynamics. We propose a different scheme. Based on simulation studies and various experiments, we suggest that the pointwise dimension of EEG time series may provide some valuable information about underlying neuronal generators.

LABORATORY-DOCUMENTED HALLUCINATION DURING SLEEP-ONSET REM PERIOD IN A NORMAL SUBJECT

During an experiment on nocturnal sleep interruption, we observed a unique case of hallucination without sleep paralysis during the sleep-onset REM period in a normal individual. We documented the polysomnogram recorded during this hallucination. The polysomnogram showed a mixed pattern of Stages REM and W, with muscle-tone inhibition, rapid eye movements (REMs), slow eye movements (SEMs), and abundant alpha EEG trains. The blocking of alpha EEG trains by REMs appeared to reflect visual processing similar to that which occurs during waking. This hallucination was distinct from ordinary sleep-onset mentation in that it included strong emotional components and in that the subject simultaneously experienced both hallucinatory mentation and reality contact. This hallucination may resemble sleep paralysis with regard to its physiological and psychological background, and the discrimination of these two phenomena may depend on the subject's own awareness of muscle-tone inhibition.

Laboratory-Documented Hallucination during Sleep-Onset Rem Period in a Normal Subject

During an experiment on nocturnal sleep interruption, we observed a unique case of hallucination without sleep paralysis during the sleep-onset REM period in a normal individual. We documented the polysomnogram recorded during this hallucination. The polysomnogram showed a mixed pattern of Stages REM and W, with muscle-tone inhibition, rapid eye movements (REMs), slow eye movements (SEMs), and abundant alpha EEG trains. The blocking of alpha EEG trains by REMs appeared to reflect visual processing similar to that which occurs during waking. This hallucination was distinct from ordinary sleep-onset mentation in that it included strong emotional components and in that the subject simultaneously experienced both hallucinatory mentation and reality contact. This hallucination may resemble sleep paralysis with regard to its physiological and psychological background, and the discrimination of these two phenomena may depend on the subject's own awareness of muscle-tone inhibition.

Neuropsychological assessment of subjects with uncontrolled epilepsy: effects of EEG feedback training.

A battery of neuropsychological tests was administered at baseline, postcontrol period, and posttraining period to 24 drug-refractory subjects with epilepsy participating in a study of sensorimotor electroencephalographic (EEG) normalization feedback training. Results revealed the following. First, subjects exhibited significant baseline deficits in psychosocial, cognitive and motor functioning. Second, certain tests discriminated subjects before training who were subsequently above and below the median in seizure reduction following EEG training. Subjects who showed the greatest seizure reduction performed better on a test of general problem-solving ability but not on other cognitive tests and worse on tests involving strong motor components and were more intact psychosocially. These subjects also took significantly fewer medications in combination than did less successful subjects. Third, improvement on several measures occurred following participation in the study. Cognitive and motor functioning improved only in subjects with the greatest seizure reduction and only after actual training as opposed to control conditions. Psychological functioning, as measured by the Minnesota Multiphasic Personality Inventory (MMPI) improved in both outcome groups. MMPI improvement, unlike cognitive improvement, was as likely to occur after control conditions, when seizure reduction had not yet occurred, as after EEG training. Thus, MMPI changes apparently reflected the nonspecific benefits of participation in this study.

Degree of uniformity of forms of statistical dependence between the EEG and spike trains of neurons.

1. Essential similarity of forms of cross-correlograms characterizing relations between cell discharges and ECoG waves is demonstrated for neuron bodies in cortical layers V–VI located within the same vertical microelectrode track. 2. Neurons located at different distances apart (up to 1000 μ) horizontally are shown to have similar forms of cross-correlograms. The decrease in the degree of similarity of these curves with an increase in the distance apart of spontaneously active cells is nonlinear. 3. The tangential size of the functional assemblage of cortical neurons is estimated to be of the order of 140–300 μ.

Eight to Twelve Hertz Occipital EEG Training with Moderate and Severely Retarded Epileptic Individuals

Three retarded epileptic individuals, with a variety of seizure disorders, were provided with 8-12 Hz occipital EEG biofeedback training. While seizures were not totally eliminated in any of the subjects, the results of the study indicated that all subjects exhibited decreases in some aspect of their seizure activity. The inability of all of the subjects to increase 8-12 Hz activity may best be explained in terms of the differing degree of effectiveness of the feedback stimuli in terms of their functionality as reinforcers. The results of the study indicate that changes in procedures will be necessary in order to determine if 8-12 Hz occipital EEG training is effective in reducing epileptic seizures.

A study of anaesthesia depth by power spectral analysis of the electroencephalogram (EEG).

The feasibility of using computer-based EEG spectral analysis to monitor the level of anaesthesia during nitrous oxide-alphaprodine anaesthesia has been established by this study. At present, this system is capable of estimating the level of anaesthesia correctly from 55 per cent to 80 per cent of the time. There are several possible clinical applications of such a monitoring system during anaesthesia. It provides a continuous estimation of the depth of anaesthesia, without requiring any special EEG training on the part of the anaesthetist. This system can also be of particular benefit during anaesthesia for critically ill patients, or in specific cases, as in neurosurgery and caesarian section when there may be periods of time when the gross clinical evaluation of depth of anaesthesia may not be precise or reliable and yet it is imperative not to deepen the anaesthesia unnecessarily. In such instances it appears that a monitoring system such as we have developed could provide valuable indication of the depth of anaesthesia. Other potential applications might be in the training of students in the clinical assessment of patients during anaesthesia and in the study of new anaesthetic agents.